化学伝達物質としてのウシラクトフェリンの機能とその構造ユニットの解明

采用轻度胰蛋白酶水解乳铁蛋白，经凝胶过滤和离子交换层析分离得到牛乳铁蛋白C端半分子（C瓣）。通过测定其N端和C端氨基酸序列，并与完整乳铁蛋白的氨基酸序列进行比较，确定了该片段的身份。完整的乳铁蛋白及其片段与牛单核细胞和克氏锥虫的结合特性进行了测试。研究了其与牛乳铁蛋白的特异性结合。采用层析法从成熟的牛乳中分离得到乳铁蛋白，并用^<125>I-Bolton-Hunter试剂进行标记。结合实验发现，乳铁蛋白可以特异性地与牛单核细胞结合。完整的乳铁蛋白对克氏锥虫（无马鞭毛虫）具有结合能力。然而，牛乳铁蛋白C端半分子失去了对克氏锥虫的结合能力。从小鼠胚成纤维细胞培养中获得克氏锥虫无刚体。采用fitc标记的抗牛乳铁蛋白抗体（兔）直接免疫荧光法研究其结合。

The C terminal half molecule (C lobe) of bovine lactoferrin was isolated by mild tryptic hydrolysis of lactoferrin followed by gel filtration and ion-exchange chromatography. The idntity of the fragment was established by determining its N terminal and C terminal amino acid sequences and comparing them with the amino acid sequence of intact lactoferrin.The binding properties of intact lactoferrin and its fragments have been tested with bovine monocyte and with Trypanosoma cruzi. The specific binding with bovine lactoferrin was studied. Lactoferrin isolated from mature bovine milk by chromatographic method was used and labeled by ^<125>I-Bolton-Hunter reagent. From the binding assay, it was found that bovine milk lactoferrin could bind to bovine monocyte, specifically. And intact lactoferrin showed the binding ability to Trypanosoma cruzi (amastigote form). However, C terminal half molecule of bovine lactoferrin loses the binding capacity against Trypanosoma cruzi. Amastigote of Trypanosoma cruzi was obtained from mouse embryo fibroblast culture. The binding was studied by the method of the direct immunofluorescence test using FITC-labeled anti-bovine lactoferrin antibody (rabbit).